Study On Energy-Saving And Fault-Tolerant Algorithms For Wireless Sensor Networks Based On Topology Control

Being the important spread carrier of internet of things and key technique of extending internet coverage, wireless sensor networks has hugely potential value of application in military, environmental, medical, transportation and many other domains, and is one of the hot spot in distributed computing and wireless communication area. Due to its limited energy and frequent failure of node and link when deployed in adverse circumstances, it become the goal of optimization design of the networks how to maximize the network lifetime and improve the fault-tolerant capability of network to respond the failure. Topology control, as the key technology of wireless sensor networks, significantly reacts on saving energy consumption, prolonging network lifetime on the one hand, and can improve the fault-tolerant capability of network to respond the failure so as to provide reliabie topological structure for upper layer application. Therefore, it has both theoretical and practical significance to study on efficient energy saving and fault-tolerant topology control algorithms of wireless sensor networks. In this thesis, the problem of topology optimization of the networks is studied to design efficient energy saving and fault-tolerant topology control algorithms. The research of this thesis can provide theoretic guidance for practical applications of wireless sensor networks and develop the academic research of wireless sensor networks. The specific works are as follows:Due to the problem that the energy consumption of minimum connected dominating set is not minimum in homogeneous networks, defining energy cost function constructed by remain energy, neighborhood numbers and communication cost of nodes as topology weight to synthetically reflect the energy efficiency of dominator and the contribution of reduced whole energy consumption, an energy cost based topology control algorithm for minimum-total-weight connected dominating set ECMCDS is proposed. The algorithm locally selects the node with a low-weight undertaking dominating mission to construct minimum-total-weight dominating set, and minimums the total energy consumption of networks.The issue of minimum energy consumption topology construction for heterogeneous wireless sensor networks has been studied. Considering the heterogeneous feature of sensor nodes'communication capabilities, a function named area energy consumption rate has been built by integrating the quality of communication links, the transmission range and the remaining energy of nodes. This function has been used to estimate the energy consumption rate of communication areas and determine the selection of dominating nodes, and thus a distributed topology control algorithm AECR-CDS which is minimum connected dominating has been proposed.Considering the contradiction between energy efficiency and load balance in clustering topology of wireless sensor networks, a game theory based energy balance clustering topology control algorithm GTEBC is proposed. A new game model is build by using communication cost of cluster head and cluster member to construct the utility function which reflects energy efficiency and load balance of networks. Then the clustering topology is constructed to optimize the energy efficiency and load balance of networks together by game theory.On the question that lower energy efficiency and restricted fault tolerant ability of the fault-tolerant topology under the k-connected graph, a kind of fault-tolerant topology control algorithm FTCB based on backup mechanism is proposed. The node reliable degree and correlativity were integrated, and the fault tolerance degree metric are constructed to evaluate the node fault-tolerant ability, furthermore the use of fault tolerance degree as standard to set up the network connected dominating set, meantime, the backup backbone is built based on the thinking of backup, then the topology tolerance of node failure because of self factors and outside interference was increased efficiently.How to construct the energy optimal fault tolerant network topology on the demand of reliable service is studied. Starting with analyses of node failure mechanism, the estimation model of node failure probability is built. We analyze it and find that there is an optimal node-degree which assures the node to fit the reliability demand and maximize its lifetime simultaneously. On the basis of this, a distributed fault tolerant topology control algorithm DRTCA is presented, which maintaining the number of neighbors of every node equal to or slightly below the optimal node-degree, and constructing the optimal network topology with guarantee fault tolerant of networks which provide a new method for fault-tolerant topology control in flat networks.